1. Field of the Invention
This invention relates to the preparation of ortho substituted phenylamines from phenyl-hydroxylamine and nucleophilic reagents, such as amines and alcohols. o-Phenylenediamines, and more specifically, o-aminodiphenylamine are illustrative of the ortho substituted phenylamines formed in this invention.
2. Description of Related Art
Ortho substituted phenylamines find a variety of utilities depending upon the ortho substituent. They are used, inter alia: in dye formulations; as intermediates in electrolyte compositions; to generate photosensitive compounds; as lubricant antioxidants, viscosity improvers, and dispersants; to generate scale disposition preventers; as intermediates in thermal transfer agents; and to generate adhesives.
The syntheses of ortho substituted phenylamines vary depending upon the ortho substituent and often require several steps, which add undesirably to production costs.
It is known that phenylhydroxylamine reacts with nucleophilic reagents in the presence of aqueous inorganic acids to yield p-substituted phenylamines. See, for example, Heller, H. E. et al., Nature, 168:909 (1951) and Bamberger, E., Justin Liebig's Annalen der Chemie, 390, 139-144 (1912): Ibid., 424, 243-245, 294-296 (1921). It is disclosed that phenylhydroxylamine is converted to p-hydroxylaniline in the presence of dilute sulfuric acid. It is further taught that phenylhydroxylamine reacts with aniline in the presence of dilute sulfuric acid to yield p-aminodiphenylamine. It is also disclosed that phenylhydroxylamine is converted to ortho and p-chloroaniline when the acid employed is hydrochloric acid. Disadvantageously, Bamberger describes multiple by-products, including benzadiene, azoxybenzene and aniline. In a practical sense, there is an added disadvantage in that separation of the acid from the product stream can be expensive. The acid must be neutralized creating a waste stream, which must be disposed of.
It is known that reacting phenylhydroxylamine with aniline in the presence of a homogeneous acid catalyst or a solid acid catalyst can lead to p-aminodiphenylamine. See, for example, Smith, G. V. et al., Catalysis of Organic Reactions, Vol. 68, Marcel Dekker, New York (1996) pp. 335-342.
It is disclosed that phenylhydroxylamine and aniline in the presence of concentrated HCl, HZSM-5, HY zeolites, Nafion, filtrol (acid clay), NaHSO4/SiO4, or montmorillonite yield p-aminodiphenylamine. In each case, the predominant isomer of aminodiphenylamine was the para isomer.
U.S. Pat. Nos. 5,574,187 and 5,689,007 disclose processes of preparing para substituted phenylamines, such as, p-phenylenediamines, and particularly, p-aminodiphenylamine. One process involves contacting phenylhydroxylamine with a nucleophilic reagent, such as aniline, in specified proportions and within a specified temperature range, in the absence of oxygen, and in the presence of a homogeneous acid catalyst, such as hydrochloric acid. A second process involves contacting phenylhydroxylamine with a nucleophilic reagent, such as aniline, in the presence of a solid acid catalyst, such as acidic zeolite Y, under reaction conditions.